Side-by-side windows
I get the impression that most people browse the internet and use the computer with full-screen windows. It seems like a waste of space to me because the screen has so much horizontal space. It's actually much harder to read text when it's very wide, that's why websites tend to be constrained into a narrow column instead of spanning the whole screen, even if they sometimes go too far with it.
I've always been using windows side-by-side, usually with a browser window taking up one half or 2/3 of my screen, with other programs and a slice of the desktop on the other side, perhaps a video playing in the corner.
If the desktop is visible, I can drag and drop images into it to save them very quickly without having to think about it. The desktop also works as a place to put files that I can organize later so I don't have to think about it immediately.
This influences how I design websites and programs a bit, I always make sure it works with a narrow-ish window. I have a bad habit of not thinking much of the other case though, so I don't think about how to use the space if the window IS wide. Maybe it's something I can learn to think about it with this website.
This way of using the computer also makes me appreciate games whose window can be resized freely.